Section outline

  • A girl smiling while peeking from behind a mirror, creating a mirrored effect.

    Is this a picture of one girl peeking out from behind a mirror or is this a picture of twins designed to look like a mirror image? As in plane mirror images, the right hand of the object becomes the left hand of the image. It seems this is a mirror image or at least one created by a computer.
    ::这是一张女孩从镜子后面偷看的照片,还是一幅双胞胎照片,设计成像镜像的图像?在平面镜像中,物体的右手变成图像的左手。这似乎是镜像图像,或至少是计算机制作的。

    Image in a Plane Mirror
    ::在平面镜像中的图像

    The sketch below shows how we see an image in a plane mirror. Plane mirrors work because the light rays create a virtual image  behind the mirror. Light rays from the object strike the mirror and reflect according to the law of reflection . When some of the light rays enter our eye, our eye and brain interpret these rays as having traveled in a straight line path. Therefore, our eye and brain track the light rays backward to a position from which they appear to have come. At this position, we see an image.
    ::下面的草图显示了我们如何在平面镜子中看到图像。 平面镜子起作用, 因为光线在镜子后面创造了虚拟图像。 物体的光线照镜子, 根据反射法则反射。 当一些光线进入我们的眼睛时, 我们的眼睛和大脑将这些光线解释为在一条直线路径上行走。 因此, 我们的眼睛和大脑将光线跟踪到它们似乎从那里来的位置上。 在这个位置上, 我们可以看到一个图像 。

    Light Rays Reflecting In A Plane Mirror, Forming A Virtual Image.

    In a plane mirror, the image will be the same size as the object and will be the same behind the mirror as the object is in front of the mirror. This image is called a virtual image because the light does not actually pass through the image.
    ::在平面镜中,图像将与对象的大小相同,在镜子后面的图像与镜子前面的图像相同。这个图像被称为虚拟图像,因为光不会通过图像。

    A woman cleans a mirror, showing a reflection that appears reversed.

    When you look at an image of yourself in a plane mirror, there are some differences that are apparent. In the image above , you see a woman cleaning a mirror. The object woman has  a cleaning cloth in her right hand. The image woman, however, appears to be holding the cleaning cloth in her left hand. Although the images in a plane mirror a ppear to flip horizontally, it is actually a result of them  reversing in  depth  along the z-axis (in and out).
    ::当你用飞机镜子看自己的图像时,有一些明显差异。在以上图像中,你看到一个女人清洗镜子。对象妇女右手有清洁布。不过,图像妇女似乎把清洁布放在左手。虽然飞机镜子中的图像看起来是水平翻转,但实际上是在Z轴(内向和外向)的深度反转的结果。

    To learn more about why images in a mirror appear to flip horizontally watch the video below:
    ::更多了解为何镜子中的图像会横向翻转,

     

     

     

    Launch  the PLIX Interactive below to further explore virtual images and try to determine why you see a “mirror image” of yourself when you look at your :
    ::在下面启动 PLIX 互动, 以进一步探索虚拟图像, 并试图确定为什么当你看到自己的“美景图像 ” :

     

     

    Example  
    ::示例示例示例示例

    A person 1.80 m tall stands in front of a plane mirror. What is the minimum height of the mirror, and how high must its lower edge be above the floor for the person to be able to see his/her whole body? Assume the person’s eyes are 6.0 cm below the top of the head.
    ::1.80米高的人站在平面镜子前。 镜子的最低高度是多少,其下边缘必须有多高才能在地板上看到整个身体? 假设他的眼睛在头部下方6.0厘米以下。

    The law of reflection tells us that the angle of incidence equals the angle of reflection . From this, we know that the light ray leaving the person's toes will strike the mirror halfway between his toes and his eyes. The distance from the person’s toes to eyes is 1.74 m, so the bottom of the mirror must be 0.87 m above the floor. The light ray that leaves the top of the person’s head and reflects from the mirror into his eyes must strike the mirror 3.0 cm below the top of his head.
    ::反射法则告诉我们,事件角度等于反射角度。 从这一点看,我们知道留下脚趾的光线会击中脚趾和眼睛中间的镜子。 从脚趾到眼睛的距离是1.74米,因此镜子底部必须在地板上方0.87米。 离开人头顶并从镜子中反射到他眼睛的光线必须击中头顶下方3.0厘米的镜子。

    Light Rays Reflecting In A Plane Mirror, Illustrating Reflection Principles.

    Therefore, the top of the mirror is 1.77 m above the floor and the bottom of the mirror is 0.87 m above the floor. The height of the mirror is @$\begin{align*}1.77 \ m - 0.87 \ m = 0.90 \ m\end{align*}@$ .
    ::因此,镜子的顶部是地板上方1.77米,镜子的底部是地板上方0.87米。镜子的高度是 @$\ begin{ align} 1.77\ m - 0.87\ m= 0.90\ m\ end{ leign}$。

    It doesn’t take much analysis to recognize that the distance the person stands from the mirror does NOT affect the results. If you can’t see your feet in a mirror, getting closer or farther away from the mirror won’t make any difference.  Try it out in this simulation below by adjusting the distance to the mirror and the length of the mirror:
    ::并不需要多少分析来确认人们距离镜子的距离不会影响结果。 如果你无法在镜子里看到你的脚,那么接近镜子或离镜子更远不会有什么区别。 在下面的模拟中试一试,调整镜子的距离和镜子的长度:

     

     

    Further Reading
    ::继续阅读

    Summary
    ::摘要

    • Our eye and brain interpret any light rays that enter an eye as having traveled in a straight line path.
      ::我们的眼睛和大脑将进入眼睛的任何光线解释成 沿着一条直线行走。
    • For a plane mirror, the image will be the same size as the object and will be the same distance behind the mirror as the object is in front of the mirror.
      ::对于平面镜来说,图像的大小与对象的大小相同,在镜子后面的距离与在镜子前面的物体相同。
    • Since the light forming the image does not pass through the image, it is called a virtual image.
      ::由于形成图像的光不通过图像,它被称为虚拟图像。
    • Images in a plane mirror are reversed left and right but are not reversed top and bottom.
      ::平面镜中的图像向左和向右反转,但不向上和向下反转。

    Review
    ::回顾

    1. A virtual image is one:
      1. toward which light rays converge but do not pass through.
        ::光线交汇而不会经过的。
      2. from which light rays diverge but do not pass through.
        ::光线离它而异,它不经过。
      3. from which light rays diverge as they pass through.
        ::光明的光线,随着光线的穿透,而各有不同。
      4. toward which light rays converge and pass through.
        ::光线交汇而通过。
      5. with a ray normal to a mirror passing through.
        ::用正常的射线 穿过镜子的镜子

      ::虚拟图像是一个: 光线汇合但不会经过的光线。 光线不同但不会经过的光线。 光线经过时, 光线也不同。 光线汇合和穿过的光线。 光线正常地穿过镜子。
    2. An object is 2.0 m in front of a plane mirror. Its image is:
      1. virtual, inverted, and 2.0 m behind the mirror.
        ::虚拟的,倒转的, 和2.0米的镜子后面。
      2. virtual, inverted, and 2.0 m in front of the mirror.
        ::虚拟的,倒转的, 和2.0米在镜子前。
      3. virtual, erect, and 2.0 m in front of the mirror.
        ::虚拟的,勃起的, 和2.0米在镜子前。
      4. real, erect, and 2.0 m behind the mirror.
        ::真实的,勃起的, 和2.0米的镜子后面。
      5. virtual, erect, and 2.0 m behind the mirror.
        ::虚拟的,勃起的, 和2.0米的镜子后面。

      ::一个物体在平面镜子前为2.0米。 它的图像是: 虚拟的, 倒向的, 镜子后为2.0米。 虚拟的, 反向的, 反向的, 镜子前为2.0米。 虚拟的, 反向的, 反向的, 反向的, 反向的。 虚拟的, 直立的, 反面的, 和2.0米。 反向的, 真实的, 直立的, 反面的, 和2.0米的。 反向的, 虚拟的, 直立的, 反射的, 和2.0米的。
    3. If the angle of incidence for an object and a plane mirror is 30°, what is the angle between the object and its image?
      1. 30°
      2. 60°
      3. 90°
      4. 120°
      5. 180°

      ::如果物体和平面反射镜的发生角为30°,物体与其图像之间的角是什么? 30° 60° 90° 120° 180°
    4. If the angle of a car’s windshield is 45° to vertical, what position of the sun is most likely to reflect into oncoming driver’s eyes?
      1. Low in the sky behind the oncoming driver’s car
        ::驾驶车即将到来的车身后天空下低空
      2. Low in the sky opposite the oncoming driver’s car
        ::驾车司机的车在即将到来的司机汽车对面的天空下低空
      3. Directly overhead
        ::直接间接费用

      ::如果汽车的挡风玻璃角度从45度到垂直,太阳的位置最有可能反射到驾驶员的眼部,那么太阳的位置最有可能反射到哪个位置? 驾驶员的车尾的天空下低空,驾驶员的车尾的后面是低空。 驾驶员的车尾对面的天空下低空。 驾驶员的汽车右上方是低空。
    5. A 50. cm tall object is 3.0 m from a plane mirror. 
      1. How tall will the image be? 
        ::图像会有多高?
      2. How far from the mirror will the image be? 
        ::图像离镜子有多远?
      3. Will the image be real or virtual? 
        ::图像是真实的还是虚拟的?
      4. Will the image be upright or inverted?
        ::图像是直立还是颠倒的?

      ::50厘米高的物体距离平面镜3.0米。 图像有多高? 图像离镜子有多远? 图像是真实的还是虚拟的? 图像是直立的还是倒置的?
    6. Which statement is true about the image produced by a plane mirror?
      1. It appears to be located on the same side of the mirror as the object.
        ::它似乎位于镜子的同一侧,与物体相同。
      2. It appears to be larger than the object.
        ::它似乎大于对象。
      3. It appears to be inverted relative to the object.
        ::与对象相比,它似乎被反转。
      4. It appears to be reversed left and right.
        ::它似乎被左右反转。

      ::对平面镜中生成的图像来说,哪个语句是真实的? 它似乎位于与对象相同的反射面上。 它似乎大于对象。 相对于对象, 它似乎被反转。 它似乎被左右反转 。
    7. A light ray strikes a plane mirror at an angle of 80° to the normal. What is the angle that the reflected ray makes with the surface of the mirror?
      ::反射线与反射镜表面的角是多少?
    8. A laser beam strikes a plane mirror with an angle of incidence of 38°. What is the angle between the incident beam and the reflected beam?
      ::射线射向射线镜,射线角为38°。 事件光束与反射光束之间的角是多少?

    Explore More
    ::探索更多

    Use this resource to answer the questions that follow.
    ::使用此资源回答下面的问题 。

     

     

    1. Are the images in the plane mirror upside down?
      ::飞机镜子里的图像是不是颠倒了?
    2. Are the images in the plane mirror reversed left and right?
      ::飞机镜子上的图像是左右反转的吗?